A cassette type register memory is known, which is used as a part of a processor in some digital computers, and comprises N n-bit registers, which are serially connected from the first towards the last and vice versa through strobing circuitry for paraphase connection of the registers. This circuitry uses 2n "AND-gates" connected to a control bus in order to transfer the contents of the registers from the first towards the last, i.e. to copy the contents of the first into the second and for the exchange of contents between the first and the second register.
The shortcomings of a cassette memory of this type are: it is impossible to record or retrieve data which was already been manipulated, without violating the order of the data in the memory; and, it is impossible to exchange data between arbitrary registers of the device without taking the data out of the device.
A memory stack is also known which has an indicator for the currently active cell of the stack and the memory cells.
The shortcomings of this stack, which differs from the cassette type memory, are that it is slower in reading into and writing from the memory, and the stack consumes part of the operative memory part of the processor of a digital computer.